Synthesis of new coumarin schiff-Base for Zn~(2+) fluorescence sensoring

A novel Schiff-base compound 6-chloro-3-[( 2-hydroxy-benzylidene)-amino]-chromen-2-one( CHS)containing 3-amino-6-chloridecoumarin as fluorescent chromophore was synthesized and evaluated for Zn2 +chemosensors by the naked eye. Elemental analysis and various physic-chemical techniques including FTIR,1HNMR, UV-Vis and fluorescent spectral analysis were performed to characterize the structure and physicochemical properties. The compound exhibited strong fluorescence response toward Zn2 +via significant fluorescent change,and the color changed from colorless to yellow. Moreover,other metal ions had no obvious effect on its specific response to Zn2 +. The 1: 1 binding mode was proposed based on the Job 's plot,and the binding constant between CHS with Zn2 +was calculated to be 9. 97 × 102 mol / L by Benesi-Hildebrand equation( adsorption method). Chelation enhanced fluorescence( CHEF) mechanism was considered to account for the fluorescence enhancement and spectral redshift. In DMF solution of CHS,fluorescent emission intensity change was proportional to Zn2 +concentration in the range of 10 ~ 60 μmol / L with the detection limit of 1. 92 μmol / L( r = 0. 9907,S /N = 3),suggesting that CHS can allow the detection of micromolar Zn2 +.